Complexity has been understood in different ways since its (re)introduction into scientific discourse. Therefore, instead of proposing a definition of complexity, we group the existing explanations about it into two distinct categories: descriptive and perceived complexity. The main features of these categories are described and how they arise as the result of the adoption of contrasting epistemologies is discussed. These categories together with their implications for our doing in the world are explored under the rubric of the ‘epistemological problem of complexity’. The practical significance of the issues we address, especially as they relate to building capacity for systems practice, understood as a way of managing in situations of complexity, is also of concern. “Even when the individual trees are highly interesting and picturesque, it has use to see what the forest looks like in the large” (Rescher, 1998: xvii).